JP2000083355A - Bar jack testing machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To minimize disassembly of a generator and enable measurement of the movement of a stator bar by designing the bar jack tester so that a displacement measuring arm unsymmetrically pressed by a spring presses a bar sensor via a shaft bracket, in such a direction that it is engaged with the stator bar. SOLUTION: This bar jack tester 17 is installed on a jack device and is engaged so that it works together with a bar jack testing head 16 positioned between a stator bar 53 and a retaining ring 73. The displacement measuring arm 36 of a linear voltage displacement transducer(LVDT) 32 is pressed unsymmetrically outwards by a compression spring 38. The LVDT 32 communicates with a measurement controller and processes measured distances. The displacement measuring arm 36 is installed at the end of a shaft bracket 40 which pivots on a shaft 42 installed on a frame 34, end of which faces is opposite the cross pin 101, and pressed so that the displacement measuring arm is engaged with the stator bar 53 of the generator. A bar sensor 44 penetrates the bar jack testing head 16 and is engaged with the stator bar 53.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

FIELD OF THE INVENTION The present invention relates to a stator bar jack device,
More specifically, it relates to a pneumatic jack device used to measure the radial movement of the stator bar in its slot while the generator is in its place.

[0002]

BACKGROUND It has been found that stator bar vibrations caused by radial gaps between the bars and stator slots are important factors contributing to stator bar wear. The stator windings are designed and assembled such that there is no gap in the slot. However, radial gaps are created in the stator slots as a result of the gradual shrinkage of the slot contents such as bar armor, slot fills and wedges that can occur in the stator windings during normal long term operation. . Early detection of the occurrence of this gap allows the generator owner to take necessary corrective actions before the wear causes significant damage to the ground insulation of the stator bar. For this reason, the jack device is suitable as a generator maintenance planning tool for confirming a part and a work range for a main shutdown for maintenance.

The method currently used to measure the radial movement of the stator bar in the slot requires that the field of the generator be removed from the stator. Due to the time required for the field disassembly and removal, the process, and the danger of removing the field, the measurement of this radial movement has been omitted from the shutdown plan. Typically, one stator bar is pressed against radially opposed bars using a hydraulic jack with a special jack board, and its movement is measured using a dial indicator.

[0004]

DISCLOSURE OF THE INVENTION A bar jack device according to the present invention comprises:
During a short outage for inspection, generator disassembly is minimized to enable such measurements and valuable information for planning work areas and parts for the main outage for inspection. To be able to collect.

This jack device is designed to pass through a radial gap between the field holding ring and the stator end winding. This requires a minimum entrance clearance of 2.625 inches. The device is delivered by a miniature crawler to the location of interest where the movement is to be measured. The crawler is configured to circumferentially position the device along a holding ring. The device is placed between the presser ring and the stator bar to be measured by applying a force driven by air pressure or the like. The location where the movement of the stator bar is measured is typically the straight portion of the radially inner stator bar at the exit of the slot. The air pressure is 100 per inch of contact length between the device and the bar.
Adjusted to apply pound force. The radial movement of the bar resulting from the application of this force is measured by a linear voltage displacement transducer (LVDT) and transmitted to the measuring device.

In one aspect of the present invention, there is provided a bar jack test apparatus for measuring radial movement of a stator bar of a generator at a location. A bar jack test apparatus includes an LVDT secured to a frame and including a spring biased displacement measurement element. A bar sensor may engage the stator bar at the outer end. A pivot bracket is pivotally attached to the frame and is located between the inner end of the bar sensor and the spring biased displacement measuring arm of the LVDT. The spring biased displacement measurement arm pushes the bar sensor in a direction to engage the stator bar.

In another aspect of the present invention, there is provided a bar jack crawler for measuring radial movement of a stator bar of a generator at a location. A bar jack crawler includes a jack assembly that can be inserted into the radial gap between the generator field hold-down ring and the stator end turns. A bar jack test head is mounted on the jack assembly and a bar jack test device is operatively associated with the bar jack test head.

The above and other aspects and advantages of the present invention will be described in detail below with reference to the drawings.

[0009]

FIG. 1 is a plan view of a bar jack crawler 10 according to the present invention. The crawler 10 mainly includes a tractor portion 12 that circumferentially positions a bar-jack test head 17 and a jack assembly 14 around the generator field. Jack assembly 1
4 cooperates with a bar jack test head 16 engaged with a bar jack test apparatus 17 (FIG. 2).

The tractor section 12 uses a DC motor 18 that transmits power to two coupled drive gears 20. A drive gear 20 rolls along the track in a circumferential direction along the holding ring. Passing the trucks over the respective idler pulleys 24 removes slack in the drive truck. Pulley 2
4 are located at the ends of two pneumatic rams 26, these rams being actuated by pressurized air,
Press 4 on the truck.

Referring to FIG. 2, a bar jack test apparatus 17 is mounted on the jack apparatus 14 and cooperates with a bar jack test head 16 positioned between the stator bar 53 and the retaining ring 73. Engage.
The bar jack tester 17 includes a linear voltage displacement transducer (LVDT) 32 fixed to a frame 34. LV
DT is a common device for accurately measuring small distances. In this context, the LVDT 32 has a spring-biased displacement measuring arm 36 which is mounted on a spring-biased displacement measuring arm 36.
8, the pressure is outwardly biased. The LVDT communicates with the measurement controller (not shown) to process the measured distance.

A displacement measurement arm 36 is mounted on the frame 34 and engages with a pivot bracket 40 that pivots about a pivot 42. A bar sensor 44 is mounted at the end of the pivot bracket 40 opposite the cross pin 101 and is pressed (upward in FIG. 2) into engagement with the stator bar 53 of the generator. As shown in FIG. 2, the bar sensor 44 passes through the bar jack test head 16 and engages the stator bar 53 of the generator. To minimize local stresses on the insulating material covering the bar,
A flexible pad 6 is provided on the upper surface of the bar jack test head 16.
4 are provided. For this purpose, a flexible pad 6
4 is preferably formed of high density polyethylene (HDPE). Of course, other materials such as urethane may be used and the invention is not limited to HDPE.

A frame 34 is pivotally mounted on the bar jack chassis 100. A presser ring sensor 46 is secured to the frame 34 and engages a presser ring 73 through a hole in the chassis 100. As the frame 34 is pivotally attached to the chassis 100, the sensor 46 is kept in engagement with the holding ring. The underside of the chassis 100 is coated with a wear-resistant plate 103, which is preferably made of HDPE or other similar material that does not scratch the retaining ring.

Referring to FIGS. 3 and 4, jack assembly 14 has a wedge driver 52, such as a pneumatic ram, including a drive piston 54. A wedge 56 is coupled to the drive piston and includes a wheel 56a mounted on a steel plate 57 to facilitate positioning and driving of the wedge 56. A lifting arm 58 is movably engaged with the wedge 56 at a first end, for example by a wheel 58a, and
Is fixed to the pivot 60 at one end. The lifting arm 58
At an intermediate portion, such as a pivot 62 between the first and second ends,
The bar jack test head 16 is supported.

As shown in FIG. 4, when wedge driver 52 drives wedge 56 via piston 54 toward bar jack test head 16 (to the left as viewed in FIGS. 3 and 4), lifting arm 58 Wheel 58a is pushed up by the wedge 56, thus the bar jack test head 1
6 is correspondingly lifted to the stator bar 53. The wedge driver is controlled to apply a predetermined amount of force to the bar. In a preferred form, a force of about 100 pounds per inch of contact length between the device and the bar is applied. In practice, the movement of wedge 56 is very small, since the allowable movement of the bar is typically a few thousandths of an inch. The actual acceptable offset will vary from generator to generator. In one embodiment, the force of the jack is determined by the air pressure applied to the wedge driver 52. In another configuration, a load sensor is inserted between the wedge 56 and the piston 54 so that the load can be determined more directly.

In operation, the flexible pad 64 is pressed against the bar 53 during operation. For illustrative purposes, FIG. 2 shows the flexible pad 64 slightly away from the bar 53. To test the tightness of the bar 53, a load is applied to the bar by the jack assembly 14. The press ring 73 receives a reaction force of this load. The change in distance between the bar 53 and the presser ring 73 is measured by the relative movement of the bar sensor 44 and the presser ring sensor 46. As can be seen from the foregoing description, the hold down ring sensor 46 is securely coupled to the frame 34, which is pivotally connected to the bar jack chassis 100. This pivoting ensures that the sensor 46, which enters a hole in the chassis 100, remains in contact with the retaining ring 73. As the sensor 44 slides within the frame 34, the pivot bracket 40 rotates about its pivot 42. The spring 38 causes the displacement measurement arm 36 of the LVDT 32 to remain in contact with the pivot bracket 40. The distance measured by the sensors 44, 46 is
Jack assembly 14 and bar jack chassis 10
It is not affected by the relative position of 0.

The structure of the present invention allows the location of the stator bar to be tested in-situ without disassembling the field of the generator. The jack device is circumferentially positioned along the field by the tractor portion and inserted into the radial gap between the field retaining ring and the stator end turns. Further maintenance can be performed if the radial movement of the bar as a result of the application of force exceeds the threshold limit.

Although the present invention has been described in what is presently considered to be the most practical and preferred embodiment, the present invention is not limited to the embodiments disclosed herein, but, rather, various changes and modifications are within the scope of the appended claims. It should be appreciated that the configuration extends to an equivalent.

[Brief description of the drawings]

FIG. 1 is a plan view of a bar jack crawler according to the present invention.

FIG. 2 is a sectional view of a bar / jack test apparatus according to the present invention.

FIG. 3 is a side view of the bar jack crawler in a ready state.

FIG. 4 is a side view of the bar jack crawler when a force is applied.

[Explanation of symbols]

 10: Bar jack crawler 14: Jack assembly 16: Bar jack test head 17: Bar jack test device 32: Linear voltage displacement transducer (LVDT) 36: Displacement measuring arm 38: Compression spring 40: Axis bracket 44 : Bar sensor 53: Stator bar 73: Presser ring

Claims (9)

[Claims] 1. A bar jack test apparatus for measuring the radial movement of a stator bar of a generator in-situ, comprising a displacement measuring arm fixed to a frame and biased by a spring. A voltage displacement transducer (LVDT), a bar sensor capable of engaging a stator bar at an outer end, and an inner end of the bar sensor pivotally attached to the frame and an LV.
A pivot bracket disposed between the spring-biased displacement measurement arms of the DT, wherein the spring-biased displacement measurement arm engages the stator bar via the pivot bracket. Bar jack test equipment that presses bar sensors. 2. A holding ring fixed to said frame and adapted to engage with a holding ring of a generator.
The bar jack test apparatus according to claim 1, further comprising a sensor. 3. A bar jack crawler for measuring in-situ radial movement of a generator stator bar,
A jack assembly that can be inserted into a radial gap between the field retainer ring of the generator and the terminal winding of the stator, a bar jack test head attached to the jack assembly, and the bar jack test A bar jack tester cooperatively engaged with the head, the bar jack tester being fixed to the frame and having a spring biased displacement measuring arm. Vessel (LVD
T) a bar sensor that can engage the stator bar at the outer end;
And a pivot bracket pivotally mounted to the frame and disposed between the inner end of the bar sensor and the spring biased displacement measuring arm of the LVDT, wherein the spring biased displacement measuring arm includes A bar jack crawler that presses the bar sensor in a direction that engages the stator bar via the pivot bracket. 4. The bar jack tester of claim 3 wherein said bar jack tester further comprises a presser ring sensor secured to the frame and adapted to engage a presser ring of the generator. Crawler. 5. A wedge driver including a drive piston, a wedge mounted on the drive piston, a first end movably engaging the wedge with the wedge, and
4. A bar jack crawler as claimed in claim 3, wherein said end is fixed to a pivot and has a lifting arm supporting said bar jack test head at a position intermediate said first and second ends. 6. The bar jack test device is fixedly disposed adjacent a second end of the lift arm, and wherein the bar jack test device is
6. The bar jack crawler of claim 5, wherein a sensor passes through an opening in the bar jack test head. 7. The bar jack crawler of claim 3, wherein said bar sensor passes through an opening in said bar jack test head. 8. A tractor mountable to a field hold-down ring for selective circumferential positioning about a generator rotor, wherein said jack assembly is mounted to said tractor. A bar jack crawler according to claim 3. 9. The bar jack crawler of claim 3, wherein the bar jack test head has a flexible pad on the stator bar side of the bar jack test head.